> From: jer...@marvell.com [mailto:jer...@marvell.com]
> Sent: Thursday, 11 January 2024 16.18
>
> From: Jerin Jacob <jer...@marvell.com>
>
> Introduce a new API to retrieve the number of used descriptors
> in a Tx queue. Applications can leverage this API in the fast path to
> inspect the Tx queue occupancy and take appropriate actions based on
> the
> available free descriptors.
>
> A notable use case could be implementing Random Early Discard (RED)
> in software based on Tx queue occupancy.
>
> Signed-off-by: Jerin Jacob <jer...@marvell.com>
> ---
Generally looks good.
Only some minor suggestions/comments regarding rte_eth_tx_queue_count():
uint16_t tx_queue_id -> uint16_t queue_id
Everywhere, also in rte_ethdev_trace_fp.h.
Similarly in the log messages:
"Invalid Tx queue_id" -> "Invalid queue_id"
I don't like that rc = -EINVAL is reused instead of set explicitly for each
error case.
Also, the return value -ENOTSUP is not traced.
Consider using an "out" label for a common return path to include trace, e.g.:
/**
* @warning
* @b EXPERIMENTAL: this API may change, or be removed, without prior notice
*
* Get the number of used descriptors of a Tx queue
*
* This function retrieves the number of used descriptors of a transmit queue.
* Applications can use this API in the fast path to inspect Tx queue occupancy
and take
* appropriate actions based on the available free descriptors.
* An example action could be implementing the Random Early Discard (RED).
*
* Since it's a fast-path function, no check is performed on port_id and
* queue_id. The caller must therefore ensure that the port is enabled
* and the queue is configured and running.
*
* @param port_id
* The port identifier of the device.
* @param queue_id
* The index of the transmit queue.
* The value must be in the range [0, nb_tx_queue - 1] previously supplied
* to rte_eth_dev_configure().
* @return
* The number of used descriptors in the specific queue, or:
* - (-ENODEV) if *port_id* is invalid. Enabled only when RTE_ETHDEV_DEBUG_TX
is enabled
* - (-EINVAL) if *queue_id* is invalid. Enabled only when
RTE_ETHDEV_DEBUG_TX is enabled
* - (-ENOTSUP) if the device does not support this function.
*
* @note This function is designed for fast-path use.
*/
__rte_experimental
static inline int
rte_eth_tx_queue_count(uint16_t port_id, uint16_t queue_id)
{
struct rte_eth_fp_ops *fops;
void *qd;
int rc;
#ifdef RTE_ETHDEV_DEBUG_TX
if (port_id >= RTE_MAX_ETHPORTS || !rte_eth_dev_is_valid_port(port_id))
{
RTE_ETHDEV_LOG_LINE(ERR, "Invalid port_id=%u", port_id);
rc = -ENODEV;
goto out;
}
if (queue_id >= RTE_MAX_QUEUES_PER_PORT) {
RTE_ETHDEV_LOG_LINE(ERR, "Invalid queue_id=%u for port_id=%u",
queue_id, port_id);
rc = -EINVAL;
goto out;
}
#endif
/* Fetch pointer to Tx queue data */
fops = &rte_eth_fp_ops[port_id];
qd = fops->txq.data[queue_id];
#ifdef RTE_ETHDEV_DEBUG_TX
if (qd == NULL) {
RTE_ETHDEV_LOG_LINE(ERR, "Invalid queue_id=%u for port_id=%u",
queue_id, port_id);
rc = -EINVAL;
goto out;
}
#endif
if (fops->tx_queue_count == NULL) {
rc = -ENOTSUP;
goto out;
}
rc = fops->tx_queue_count(qd);
out:
rte_eth_trace_tx_queue_count(port_id, queue_id, rc);
return rc;
}
With or without suggested changes:
Acked-by: Morten Brørup <m...@smartsharesystems.com>
